Cuba 'sonic attack' mystery deepens

July 24, 2019 — 2.16pm

Chicago: Advanced brain scans found perplexing differences in American diplomats who say they developed concussion-like symptoms after working in Cuba, a finding that only heightens the mystery of what may have happened to them, a new study says.

Extensive imaging tests showed the workers had less white matter than a comparison group of healthy people and other structural differences, researchers said.

A classic convertible drives past the United States embassy in Havana, Cuba.Credit:AP

While they had expected the cerebellum, near the brain stem, to be affected given the workers' reported symptoms - balance problems, sleep and thinking difficulties, headaches and other complaints - they found unique patterns in tissue connecting brain regions.

Ragini Verma, a University of Pennsylvania brain imaging specialist and the lead author, said the patterns were unlike anything she's seen from brain diseases or injuries.

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"It is pretty strange. It's a true medical mystery," Verma said.

Co-author Dr Randel Swanson, a Penn specialist in brain injury rehabilitation, said "there's no question that something happened," but imaging tests can't determine what it was.

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An outside expert, University of Edinburgh neurologist Jon Stone, said the study doesn't confirm that any brain injury occurred nor that the brain differences resulted from the strange experiences the diplomats said happened in Cuba.

Cuba has denied any kind of attack, which has strained relations with the United States.

"The article published today doesn't change the situation," said Johana Tablada, Cuba's deputy head of US affairs. "The article recognises that the changes detected are minimal, that their conclusions are uncertain and that they can't identify the cause."

The results were published in the Journal of the American Medical Association on Tuesday. A journal editorial says the study may improve understanding of the reported symptoms, but that the relevance of the brain differences is uncertain.

In a statement, the US State Department said it was "aware of the study and welcomes the medical community's discussion on this incredibly complex issue. The Department's top priority remains the safety, security, and well-being of its staff."

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Between late 2016 and May 2018, several US and Canadian diplomats in Havana complained of health problems from an unknown cause. One US government count put the number of American personnel affected at 26.

Some reported hearing high-pitched sounds similar to crickets while at home or staying in hotels, leading to an early theory of a sonic attack. The Associated Press reported that an interim FBI report found no evidence that sound waves could have caused the damage.

Dozens of US diplomats, family members and other workers sought exams. The new study reports on 40 of them tested at the University of Pennsylvania. A group analysis of results from advanced MRI scans found brain differences in the diplomat group compared with 48 healthy people with similar ages and ethnic background.

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Workers had MRI tests about six months after reporting problems, but because their brains were not scanned before their Cuba stints they can't know if anything changed, a drawback of the study that the researchers acknowledge.

The University of Edinburgh's Stone said the new study has several other limitations that weaken the results, including a comparison group that wasn't evenly matched to the patients.

"If you really want to suggest that something fundamentally different happened in Cuba ... then the best control group would be 40 individuals with the same symptoms who hadn't been to Cuba and had no history of head injury," Stone said.